The invention relates to a device and arrangement suitable for grinding the inside of a pipe, for instance a pipe liner installed inside a sewage pipe, and to the use of the device for grinding the inner surface of a pipe.
In prior-art solutions, the inner surfaces of sewage pipes have been machined from inside the pipe by means of grinding robots, for example. The robot may have a spherical blade attached to the end of an arm, which blade while rotating grinds the inner wall of the pipe and may be controlled by means of appropriate control devices. The grinding blade is operated by a pneumatic motor, for example. Due to the low torque generated by the pneumatic operation, the rotation speed required for the grinding blade may be very high, such as 10 000 to 30 000 rpm. The robot is pushed to the cutting point inside the pipe by means of rigid push bars.
A problem with the prior-art solutions is that machining is slow and susceptible to errors. For example, an incorrect control command to the robot may damage not only the pipe to be machined, but also another pipe that surrounds the pipe to be machined. Further, it is often difficult to move the grinding robot inside the sewage pipe, possibly through a number of sharp turns, to the desired location. Moving through turns is not always successful, so the grinding robot often has to be used from a different end of the pipe than through which the lining was applied, in which case a drainwell on a street may have to be opened and the street closed for traffic for the duration of the machining.